Field of the Invention
Generally, the present invention is directed to novel photoactive resins. The present invention also is directed to radiation curable compositions including photoactive resins in combination with an amine and an acrylate. The present invention further is directed to radiation curable inks including pigments, radiation curable compositions and additives.
Description of the Related Art
Radiation curable compositions are distinct from other compositions. Namely radiation curable compositions have the ability to change state almost instantaneously from the fluid phase to a highly cross-linked solid phase via a chemical reaction. The chemical reaction generally is initiated by a radiation source such as ultraviolet light or high-energy electron beams.
From a commercial context, the speed at which radiation curable compositions are cured is important. For example, in the field of packaging faster caring of a radiation curable composition on a substrate results in increased throughput. By so doing, significant cost savings are obtained in view of reduced production and printing time.
Radiation curable compositions typically include a polymerizable compound. The polymerizable compound generally includes monomers such as monomeric, oligomeric or polymeric, mono- of multifunctional acrylates. Depending upon the application of the radiation curable compositions, such as, for example fast curing applications, the additives may include one or more photoinitiators to initiate free radical polymerization of the acrylate. By so doing, the radiation curable composition ultimately is hardened into a dry and solid film.
In recent years, regulations in developed countries have become more stringent with respect to migration levels of components in radiation curable compositions and inks. For example, certain classes of photoinitiators are highly prone to migration caused by unreacted and residual photoinitiator amounts. Specifically, photoinitiators having a molecular weight less than 500 Daltons are susceptible to migration resulting in odor and toxicity problems in packaging applications. Migration is common in Type 1 photoinitiators, such as, for example alpha-aminoacetophenones, which split upon irradiation and form even smaller molecules.
A need thus exists for radiation curable compositions and inks including little if any photoinitiator components which are prone to migration.
A need also exists for radiation curable compositions and inks exhibiting improved curing properties.